Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA.
Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA; Janelia Research Campus, HHMI, Ashburn, VA, USA.
Curr Biol. 2022 Aug 8;32(15):3317-3333.e7. doi: 10.1016/j.cub.2022.06.019. Epub 2022 Jul 5.
Animals communicate using sounds in a wide range of contexts, and auditory systems must encode behaviorally relevant acoustic features to drive appropriate reactions. How feature detection emerges along auditory pathways has been difficult to solve due to challenges in mapping the underlying circuits and characterizing responses to behaviorally relevant features. Here, we study auditory activity in the Drosophila melanogaster brain and investigate feature selectivity for the two main modes of fly courtship song, sinusoids and pulse trains. We identify 24 new cell types of the intermediate layers of the auditory pathway, and using a new connectomic resource, FlyWire, we map all synaptic connections between these cell types, in addition to connections to known early and higher-order auditory neurons-this represents the first circuit-level map of the auditory pathway. We additionally determine the sign (excitatory or inhibitory) of most synapses in this auditory connectome. We find that auditory neurons display a continuum of preferences for courtship song modes and that neurons with different song-mode preferences and response timescales are highly interconnected in a network that lacks hierarchical structure. Nonetheless, we find that the response properties of individual cell types within the connectome are predictable from their inputs. Our study thus provides new insights into the organization of auditory coding within the Drosophila brain.
动物在广泛的情境中使用声音进行交流，听觉系统必须对与行为相关的声音特征进行编码，以驱动适当的反应。由于映射潜在回路和对与行为相关特征的响应进行特征描述具有挑战性，因此很难解决特征检测如何沿听觉通路出现的问题。在这里，我们研究了黑腹果蝇大脑中的听觉活动，并研究了求爱歌声的两种主要模式——正弦波和脉冲列的特征选择性。我们鉴定了听觉通路中间层的 24 种新的细胞类型，并利用新的连接组学资源 FlyWire，绘制了这些细胞类型之间的所有突触连接，以及与已知的早期和高级听觉神经元的连接——这代表了听觉通路的第一个电路水平图谱。此外，我们确定了该听觉连接组中大多数突触的信号（兴奋性或抑制性）。我们发现，听觉神经元对求爱歌曲模式表现出连续的偏好，并且具有不同歌曲模式偏好和反应时间尺度的神经元在一个缺乏层次结构的网络中高度互联。尽管如此，我们发现连接组内单个细胞类型的反应特性可以从其输入中预测。因此，我们的研究为果蝇大脑内听觉编码的组织提供了新的见解。
